void add_to_menu(dish cai)
{
    FILE *f = fopen("menu.txt", "a+");
    fprintf(f, "%s\t", cai.name);
    fprintf(f, "%s\t", cai.type);
    fprintf(f, "%.1f\t%.1f\t%d\n", cai.cost, cai.price, cai.daily_supply);
    fclose(f);
}